1. Field of the Invention
This invention relates to electrical cable connectors. More particularly, the invention relates to a flat inner conductor coaxial connector with improved passive intermodulation distortion (PIM) electrical performance and mechanical interconnection characteristics.
2. Description of Related Art
Coaxial cable connectors are used, for example, in communication systems requiring a high level of precision and reliability.
During systems installation, rotational forces may be applied to the installed connector, for example as the attached coaxial cable is routed towards the next interconnection, maneuvered into position and/or curved for alignment with cable supports and/or retaining hangers. Rotation of the coaxial cable and coaxial connector with respect to each other may damage the connector, the cable and/or the integrity of the cable/connector inter-connection. Further, once installed, twisting, bending and/or vibration applied to the interconnection over time may degrade the connector to cable interconnection and/or introduce PIM.
PIM is a form of electrical interference/signal transmission degradation that may occur with less than symmetrical interconnections and/or as electro-mechanical interconnections shift or degrade over time, for example due to mechanical stress, vibration, thermal cycling, oxidation formation and/or material degradation. PIM is an important interconnection quality characteristic, as PIM from a single low quality interconnection may degrade the electrical performance of an entire Radio Frequency (RF) system.
Prior coaxial cables typically have a coaxial configuration with a circular outer conductor evenly spaced away from a circular inner conductor by a dielectric support such as polyethylene foam or the like. The electrical properties of the dielectric support and spacing between the inner and outer conductor define a characteristic impedance of the coaxial cable. Circumferential uniformity of the spacing between the inner and outer conductor prevents introduction of impedance discontinuities into the coaxial cable that would otherwise degrade electrical performance.
A stripline is a flat conductor sandwiched between parallel interconnected ground planes. Striplines have the advantage of being non-dispersive and may be utilized for transmitting high frequency RF signals. Striplines may be cost effectively generated using printed circuit board technology or the like. However, striplines may be expensive to manufacture in longer lengths/larger dimensions. Further, where a solid stacked printed circuit board type stripline structure is not utilized, the conductor sandwich is generally not self supporting and/or aligning, compared to a coaxial cable, and as such may require significant additional support/reinforcing structure.
Competition within the RF cable industry has focused attention upon reducing materials and manufacturing costs, electrical characteristic uniformity, defect reduction and overall improved manufacturing quality control.
Therefore, it is an object of the invention to provide a coaxial cable and method of manufacture that overcomes deficiencies in such prior art.